Today begins the visible peak viewing of the Perseids Meteor Shower in the Northern Hemisphere, during which meteors reach 60 mph and can be seen stretching across the sky in the constellation Perseus.
The stream or cloud of meteors consists of particles ejected by the comet Swift-Tuttle on its 130-year orbit. The dust you will be viewing is around a thousand years old. As characteristic of all meteor showers, the greatest rate of visibility is just before dawn because the side of the Earth nearest to the sun scoops up more meteors as Earth turns in space.
The comet was discovered in 1862 by Americans Lewis Swift and Horace Tuttle, the new object became favorably positioned high in the northern sky through the remainder of the summer. The French astronomer Camille Flammarion ranked comet Swift-Tuttle among the ten "really fine and striking comets" of the 19th century. Others would simply refer to it as "The Great Comet of 1862."
While peak viewing is reported to be this weekend, these swift-moving meteors start to streak across the nighttime sky by mid to late evening tonight. As twilight deepens into night, the number of meteors begins to increase. The intensity begins to build after midnight, and the greatest numbers of meteors typically explode in the sky in the dark hours just before dawn. At mid-northern latitudes, you might see 50 Perseid meteors per hour.
Why are meteors best seen at night and pre-dawn?
Meteor showers have what is called a “radiant point.” This is the point in the sky from which the meteors are visible, or “radiant.” The point needs to be above the horizon; therefore in the constellation Perseus the Hero is ascending in the northeast by midnight and is highest in the sky before dawn.
You don’t need to find Perseus to see the meteors because they will appear in all parts of the sky during those peak viewing times. If you want to find Perseus, however, look for the W-shaped constellation Cassiopeia—that naughty, vain queen--that is formed by five bright stars. It is bordered by Andromeda to the south, Perseus to the southeast. Cassiopeia is close to the Big Dipper.
August is a great month to go camping and sit under the night sky, or sit outside and plant your gaze to the heavens during the Perseids Meteor Shower. There will be a waning crescent moon before dawn and it promises not to intrude. Instead, the moon will contribute to your pleasurable viewing by guiding your eye to the brightest planets Venus and Jupiter and the constellation Orion’s Belt in the eastern sky.